class Futex:

  locked, waits = '', ''

  def tryacquire(self):

    if not self.locked:

      self.locked = '🔒'

      return ''

    else:

      return '🔒'

  def release(self):

    if self.waits:

      self.waits = self.waits[1:]

    else:

      self.locked = ''

  def t1(self):

    while True:

      if self.tryacquire() == '🔒':

        self.waits = self.waits + '1'

        while '1' in self.waits:

          pass

      cs = True

      del cs

      self.release()

  def t2(self):

    while True:

      if self.tryacquire() == '🔒':

        self.waits = self.waits + '2'

        while '2' in self.waits:

          pass

      cs = True

      del cs

      self.release()

  def t3(self):

    while True:

      if self.tryacquire() == '🔒':

        self.waits = self.waits + '3'

        while '3' in self.waits:

          pass

      cs = True

      del cs

      self.release()

locked = 🔒

waits =

t1.cs = ⊥

t2.cs = ⊥

t3.cs = True (⊥)